The present invention relates to compositions comprising acrylonitrile/styrene/acrylic ("ASA") polymeric materials and methods for making such compositions. More particularly, the present invention relates to compositions comprising ASA polymeric materials which include physical mixtures of polymers and to methods for making such physical mixture-containing compositions.
Acrylic/styrene/acrylonitrile polymeric resins are known and have been used in various applications which taken advantage of the weatherability of such resins. As used herein, the term "weatherability" refers to the ability or property of a material to effectively withstand the conditions of an out-of-doors environment over a long period of time, for example, at least five years and preferably at least seven years, with substantially no degradation or decomposition. In general, such resins have been terpolymers of an acrylate monomer, styrene monomer and acrylonitrile monomer. See, for example, Yu et al U.S. Pat. No. 3,944,631, Ting U.S. Pat. No. 4,831,079 and Ting U.S. Pat. No. 4,731,414.
In the past, such resins compositions have been produced in accordance with sequential polymerization processes in which one or more monomers are polymerized followed by one or more further polymerizations of an additional monomer or monomers in the presence of the product of the first polymerization. Such sequential polymerization processes have certain drawbacks. For example, it is relatively difficult to consistently control the various polymerization steps involved. This can lead to the economically wasteful production of materials which do not meet product specifications. In addition, such sequential polymerization processes often occur in large scale, expensive and relatively complex equipment.
It would be advantageous to provide compositions including ASA polymeric materials which have substantially uniform and controlled compositions, e.g., which consistently meet product specifications, and can be produced in a cost effective and straightforward manner.